Devices and methods offering solutions for pasteurizing a liquid product consisting of one or more components are known in the production of liquid products. Tasks of such systems or methods respectively, comprise the provision of the liquid product, the pasteurization itself and the supply of the mixed liquid product to installations for further processing. Typically, a further processing step consists in filling the liquid product into containers provided for this. For example, a variety of refreshing beverages, particularly products containing milk, etc. are produced in the food industry by means of such systems.
The pasteurization of the untreated product plays a central role in ensuring the product quality. The pasteurization is a method for which a liquid is heated up for a short period of time and is subsequently cooled down again, by which most bacteria are killed. For this, it is important that the product to be pasteurized remains a certain time under the influence of the higher temperature. This time period is called “contact time”. It is of e.g. around 30 seconds at 75 to 90° C. After this time the product is again cooled down and is deemed to be harmless for consumption. However, the contact time also depends on the temperature. In order to take into account this dependence, a variable, the pasteurization unit, has been introduced. It is calculated according to the following equation:PU=t×1.39(T-60°) 
Thereby, t is the resting time in minutes at the temperature T. In order to reach a reliable pasteurization, a substantially constant number of pasteurization units shall be maintained. Thus, according to this equation it is possible to vary the temperature, keeping the contact time constant, or to vary the contact time, keeping the temperature constant, within certain limits, such that PU remains substantially constant.
In order to satisfy this requirement, in known solutions the products to be pasteurized are guided for the required contact time through pipe coils which are kept hot. Depending on the shape of these pipe devices, like e.g. the number of deviations, the path of the product can be extended or shortened at the constant temperature by means of which the contact time can be changed. Parallel pipe systems with different features are also used, wherein the liquid to be pasteurized can be guided either through the one or through the other pipe system in order to satisfy different pasteurization requirements in the same installation.
On the other hand there are also solutions in case of which the temperature is varied, however this has the disadvantage that a temperature regulation per se is not efficient and is difficult to be realised because of the inherent inertia of such a regulation, particularly in case of small temperature variations.
Systems using a combination of both described methods are also known.
After the pasteurization the product is e.g. cooled down and transported further. Often, the product which was pasteurized in this way is filled into a so-called aseptic container, in other words a bacteria-free container, before it is supplied to e.g. a filler device. These filler devices are subject to the so-called stop-go principle, i.e. varying quantities of the liquid product are extracted non-continuously. If the delivery has to be interrupted, the product is guided back by cooling it down, as the case may be, and has to be pasteurized again because the bacteria-free state cannot be ensured anymore. If the interruption exceeds a certain time period, this process has to be repeated, with the result that the same product has to be heated up and cooled down multiple times. This can only be done a couple of times, whereafter the product is unusable because of thermal stress. The consequence is that the system has to be cleaned up by means of water and only after that new unpasteurized product can be refilled. This is disadvantageous for the operators of such systems because they loose on the one hand valuable production time and on the other hand a high quantity of the product.